1. Field of the Invention
The present invention relates to an IC socket and a semiconductor device, and more specifically, to an IC socket and a semiconductor device provided with a plurality of lead members.
2. Description of the Background Art
Conventionally, an IC (Integrated Circuit) socket for supporting an IC device or the like such that the IC device is removably connected to a circuit formed on a circuit substrate and for electrically connecting the circuit on the circuit substrate with an electrode of the IC device via a lead member incorporated within and a semiconductor device provided with such IC socket are known. The conventional IC socket will be described with reference to FIGS. 11 and 12. FIG. 11 is a schematic plan view showing the conventional IC socket, while FIG. 12 is a schematic diagram representing a semiconductor device formed with the IC socket shown in FIG. 11 disposed on the circuit substrate. FIG. 12 schematically represents a cross section of an IC socket 101 taken along the line XIIxe2x80x94XII in FIG. 11.
As shown in FIGS. 11 and 12, IC socket 101 for electrically connecting the circuit formed on a circuit substrate 107 to an IC device 104 is disposed on circuit substrate 107 which has the circuit formed thereon. IC device 104 is mounted on IC socket 101. A socket cover 103 for pressing and fixing IC device 104 against IC socket 101 is provided on IC device 104. A plurality of electrodes 131 are disposed in a matrix on the bottom wall of IC device 104. An electrode 131 is a hemispheric solder ball arranged on the bottom wall of IC device 104.
IC socket 101 is formed by a socket base body 117, a socket intermediate member 150, a socket cover body 120, and leads 106. As shown in FIG. 11, in IC socket 101, leads 106 are disposed in a matrix in positions corresponding to the plurality of electrodes 131 of IC device 104.
As shown in FIG. 13, lead 106 has a linear shape and includes a lead cylindrical body 151, an upper terminal 108, a lower terminal 130, and a spring 152. FIG. 13 is a schematic diagram illustrating the structure of lead 106. Lead cylindrical body 151 has a hollow cylindrical shape, and has an opening formed in the upper surface and an opening formed in the bottom surface. Upper terminal 108, lower terminal 130, and spring 152 are accommodated within lead cylindrical body 151. A portion of upper terminal 108 projects from the opening in the upper surface of lead cylindrical body 151, and a portion of lower terminal 130 projects from the opening in the bottom surface of lead cylindrical body 151. The diameters of the respective portions of upper terminal 108 and lower terminal 130 located inside lead cylindrical body 151 are larger than the diameters of the openings formed in the upper surface and the bottom surface of lead cylindrical body 151. As a result, upper terminal 108 and lower terminal 130 are never pushed out of lead cylindrical body 151. Spring 152 is disposed between upper terminal 108 and lower terminal 130. Thus, as shown in FIG. 12, when IC device 104 is pressed against the upper surface of IC socket 101, thereby pressing an electrode 131 against upper terminal 108 of lead 106, the reliable contact between upper terminal 108 and electrode 131 can be ensured by the elasticity of spring 152. Similarly, when IC socket 101 is pressed against circuit substrate 107, the elasticity of spring 152 ensures the reliable contact between lower terminal 130 and an electrode on circuit substrate 107.
Moreover, a sleeve-like lead protrusion 132 is formed surrounding the sidewall of lead cylindrical body 151 in the central portion of the sidewall of lead cylindrical body 151 of lead 106. In addition, as shown in FIG. 14, openings 115 and 109 which have substantially the same diameter as lead cylindrical body 151 and into which lead cylindrical body 151 can be inserted are respectively formed in socket base body 117 and socket cover body 120 of IC socket 101. An opening 110 is formed in the upper surface of socket cover body 120, and an opening 116 is formed in the lower surface of socket base body 117. FIG. 14 is a schematic perspective view of the IC socket shown in FIG. 11. Further, an opening 153 which has substantially the same diameter as lead protrusion 132 and into which lead protrusion 132 can be inserted is formed in socket intermediate member 150 of IC socket 101.
After inserting the lower portion of lead 106 into opening 115 of socket base body 117, socket intermediate member 150 and socket cover body 120 are stacked and fixed onto socket base body 117 such that lead 106 is inserted into their respective openings 153 and 109. Thus, as shown in FIG. 14, the diameters of openings 115 and 109 of socket base body 117 and socket cover body 120 are smaller than the diameter of lead protrusion 132 so that lead 106 can be fixed. IC socket 101 is thus formed.
In such IC socket 101, the elasticity of spring 152 of lead 106 can weaken as a result of deformation during use over time. As a consequence, contact failure may result between upper terminal 108 and electrode 131, or between lower terminal 130 and an electrode on circuit substrate 107. Conventionally in such a case, as shown in FIG. 15, socket cover body 120 is removed from IC socket 101, and lead 106 that has a defect is individually and manually replaced. FIG. 15 is a schematic perspective view related to the description of the lead replacement in the IC socket shown in FIG. 11.
In recent years, as IC device 104 is further miniaturized, the spacing between electrodes 131 of IC device 104 and the size of electrode 131 itself are accordingly becoming smaller. Lead 106 in IC socket 101 is also miniaturized, and the spacing of leads 106 in IC socket 101 is also made smaller. As a result, it is increasingly difficult to replace lead 106 as that shown in FIG. 15 manually with accuracy and speed. Furthermore, it is expected that the above-described problem will become more serious as IC device 104 is miniaturized even further.
Conventionally, to solve the above-described problem, an IC socket provided with a module holding a plurality of leads is disclosed, for instance, in Japanese Patent Laying-Open No. 10-125426. Moreover, Japanese Patent Laying-Open No. 7-335353 discloses an IC socket similar to the IC socket disclosed in the above Japanese Patent Laying-Open No. 10-125426. The IC sockets disclosed in the above Japanese Patent Laying-Open Nos. 10-125426 and 7-335353 can be repaired easily when a defect is found in a lead, by replacing a module that holds the defective lead.
The IC socket disclosed in the above Japanese Patent Laying-Open No. 10-125426, however, employs a lead with a curved portion. Thus, the technique disclosed in the above Japanese Patent Laying-Open No. 10-125426 is considered to be a totally different technique from that of the present invention related to an IC socket using a linear lead. Moreover, with the lead having a curved portion, the curved portion of another lead adjacent to the lead to be replaced in a module obstructs the lead to be replaced, making the replacement difficult. Such a problem does not occur, however, when a linear lead is employed as in the present invention.
The IC socket in Japanese Patent Laying-Open No. 7-335353, discloses contact blocks as modules including a plurality of leads. A contact pin serving as a lead accommodated in the contact block is a pin also having a curved portion like the IC socket disclosed in the above Japanese Patent Laying-Open No. 10-125426. For the same reason, this technique disclosed in Japanese Patent Laying-Open No. 7-335353 is considered to be a totally different technique from that of the present invention related to the IC socket using a linear lead. Furthermore, upon review by the inventor of the IC socket disclosed in the above Japanese Patent Laying-Open No. 7-335353, contact blocks serving as a module is inserted from underneath (from the circuit substrate side) into block grooves which are through-openings formed in a block housing (in other words, contact blocks are disposed directly on the circuit substrate, and no member resides between the circuit substrate and the contact blocks). Consequently, upon replacing a contact block, when the block housing is lifted upward from the circuit substrate, not only the contact block to be replaced but also other normal contact blocks tend to fall off from the block housing. Thus, a further improvement seems necessary from the viewpoint of efficiency of the replacement process of the contact blocks. As seen from the above, the above IC sockets are based on totally different techniques from that of the present invention, and are not satisfactory as far as the improvement in the efficiency of the IC socket repair process (replacement of a defective lead) is concerned.
An object of the present invention is to provide an IC socket that can improve the efficiency of the lead replacement process and a semiconductor device provided with such an IC socket.
According to one aspect of the present invention, the IC socket is removably mounted on a circuit substrate and is provided with a plurality of linear lead members, a lead module, and a socket base body. The plurality of lead members are divided into a plurality of groups, and the lead module is a replaceable lead module that holds each group of lead members and is provided in plurality to hold each of the plurality of groups. The socket base body is placed between the circuit substrate and the lead module and determines the position of the lead module against the circuit substrate.
Thus configured, a lead member having a defect can be replaced with a normal lead member by replacing the lead module that includes the lead member with the defect when such a defect is found in the lead member. In other words, the IC socket can be repaired with ease. Thus, high efficiency in the process of replacing the defective lead member with a normal lead member to repair the IC socket can be maintained even when the IC device is miniaturized, and the size of a lead member and the spacing between the lead members become smaller.
In addition, since a linear lead member is employed instead of a lead member having a curved portion, the process of removing/mounting the lead member from/to the lead module can be easily performed when a lead module having removably mounted lead members is used.
Moreover, since the lead module is disposed on the socket base body positioned on the circuit substrate, the replacement of the lead module including the lead member having a defect can be performed with the socket base body placed on the circuit substrate. Consequently, the positional relationship between the circuit substrate and the lead members included in the lead module other than the lead module that includes the lead member with a defect does not disadvantageously vary as a result of the replacement.
In the IC socket according to the above aspect, the plurality of lead members may be disposed in a straight line in the lead module.
In the IC socket according to the above aspect, the plurality of lead members may be disposed in a matrix in the lead module.
In this case, since the lead members are disposed in a matrix, a larger lead module can be obtained in which a plurality of lead modules, each having lead members disposed in a straight line, are grouped together. As a consequence, the size of the lead module can be kept large enough such that the efficiency of the replacement process does not decline when the lead members are further miniaturized. As a result, high efficiency of the replacement process of the lead module is maintained.
The IC socket according to the above aspect preferably is provided with a guide member for positioning a lead module against the socket base body.
In this case, the positioning of the lead module against the socket base body can be performed easily with the guide member so that the efficiency of the replacement process of the lead module can be improved.
In the IC socket according to the above aspect, the guide member preferably includes a guiding protrusion formed on a surface facing the socket base body of the lead module and a guiding dent formed on a surface facing the lead module of the socket base body for inserting the protrusion therein. The guiding dent preferably is formed in the socket base body in a region below the region in which the guiding protrusion of the lead module resides when the lead module is disposed on the socket base body.
In this case, the lead module can be easily positioned against the socket base body by inserting the guiding protrusion of the lead module into the guiding dent of the socket base body.
In addition, the guiding protrusion and the guiding dent can be utilized as fixing members for fixing the lead module to the socket base body so that the strength with which the lead module is fixed to the socket base body is improved.
In the IC socket according to the above aspect, the socket base body has a sidewall, and the lead module preferably includes a protrusion formed such that it projects outward from the sidewall of the socket base body.
In this case, the operator may hold the protrusion to remove the lead module from the socket base body with ease during the replacement of the lead module. Thus, the efficiency of the replacement process of the lead module can be improved further.
In the IC socket according to the above aspect, the lead module preferably includes a module base body and a module cover body. The module base body preferably holds a lead member as well as determines the position of the lead member in the lead module, while the module cover body preferably is disposed on the module base body and fixes the lead member.
Thus configured, a lead module can be provided in which a lead member is fixed to a precise position by a module base body and a module cover body.
Moreover, when the module base body and the module cover body are removably fixed by a module cover fixing member such as a screw, it becomes possible to remove only the lead member having a defect from the lead module to replace it with a new lead member. As a result, the lead module may be reused. Further, the lead member having the defect alone can be replaced as in the conventional example by removing the module cover body while the lead module remains disposed on the socket base body.
The IC socket according to the above aspect is preferably provided with a socket cover body that makes contact with the lead module.
In this case, since the socket cover body is disposed contacting the lead module, the lead module can be fixed in position by the socket cover body.
In the IC socket according to the above aspect, the socket cover body has an upper surface and a lower surface, and further, an upper through-hole which passes through the socket cover body from the upper surface to the lower surface and into which a portion of the lead member is inserted may be formed in the socket cover body. The socket base body has an upper surface and a lower surface, and further, a through-hole which passes through the socket base body from the upper surface to the lower surface and into which another portion of the lead member is inserted may be formed in the socket base body. The module cover body is preferably provided with a hole which is located underneath the upper through-hole of the socket cover body and into which the lead member is inserted. The lead member may include a lower terminal portion that projects from the lower surface of the socket base body via the through-hole of the socket base body and an upper terminal portion that projects from the upper surface of the socket cover body via the upper through-hole of the socket cover body.
Thus configured, the present invention can be applied to the IC socket that utilizes the lower terminal portion as an electrode to be connected to an electrode of a circuit formed on the circuit substrate and that utilizes the upper terminal portion as an electrode to be connected to an electrode of a semiconductor device such as an IC device mounted on the IC socket.
The IC socket according to the above aspect may respectively connect a plurality of electrode terminals on the circuit substrate to a plurality of electrode terminals of the semiconductor device. The lead member includes an elastic body, and the lead member preferably includes connecting portions that press against and make contact with an electrode terminal of the semiconductor device and an electrode terminal of the circuit substrate by the elasticity of the elastic body.
In this case, the elasticity of the elastic body is utilized to ensure a reliable contact between the connecting portions of the lead member and the respective electrode terminals of the semiconductor device and the circuit substrate so that the reliability of the IC socket can be improved.
In the IC socket according to the above aspect, the elastic body may be a spring.
In this case, an inexpensive spring that can be obtained relatively easily may be used as the elastic body so that the manufacturing cost of the IC socket can be reduced.
In the IC socket according to the above aspect, the elastic body may be formed from a conductor so that a signal may be transmitted via the elastic body from the electrode terminal of the semiconductor device to the electrode terminal of the circuit substrate.
In this case, the elastic body is utilized as a conduction line for transmitting the signal so that the structure of the lead member can be simplified.
In the IC socket according to the above aspect, the lead member may include a conductor, and the elastic body may be formed from an insulator. Thus in the lead member, a signal may be transmitted from the electrode terminal of the semiconductor device to the electrode terminal of the circuit substrate via the conductor.
In this case, a variety of materials may be utilized as the elastic body such as a resin which is an insulator so that the degree of freedom in designing the lead member can be improved.
The semiconductor device according to another aspect of the present invention is provided with the IC socket according to the above aspect.
In this manner, the IC socket can be repaired with ease when a defect is found in a lead member in the IC socket of the semiconductor device so that the repair of such a defect can be effected speedily.
The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.